This invention relates to saws and core drills used in cutting and drilling holes in hard masonry materials, and more particularly to provision and use of means coupled to a masonry saw or core drill for facilitating the cutting or drilling of concrete or other hard masonry materials.
As used herein the term xe2x80x9cmasonry materialxe2x80x9d means and includes concrete, steel-reinforced concrete, various kinds of rock including but not limited to granite, sandstone, fired brick, and tile. Special saws and drills are used for cutting and drilling those materials. Masonry saws take various forms, including rotary blade saws, ring saws, and chain saws. The drilling of lengthy holes, e.g., holes 10-20 inches long, in structures or structural components made of a hard masonry material is commonly accomplished with a core drill (also called xe2x80x9ccore drill bitxe2x80x9d) attached to a manually operated driver. A core drill commonly comprises an elongate hollow tubular member, one end of which is adapted to be releasably secured to the rotatable output shaft of a driver which typically is an electrically-powered or pneumatically-powered device. The opposite end of the tubular member is in the form of or carries a tubular cutting head that may comprise diamond or carbide particles embedded in a metal matrix. The core drill derives its name from the fact that as it drills into concrete or other dense material the interior of the drill fills with a discrete cylinder, called a xe2x80x9ccorexe2x80x9d, composed of particles of the material that is being drilled.
A common practice is to apply water to masonry saws and core drills to enhance cutting and drilling. When water is applied to saws, the sawing process is identified as xe2x80x9cwet sawingxe2x80x9d. The water is applied as a spray or jet(s) so as to flow over at least the cutting edge portion(s) of the saw device, e.g., the teeth of a chain saw or of a rotary saw blade. In the case of wet core drilling, the water is injected into the core drill. Injection of water into a core drill is accomplished by means of a coupling device that either is a component of the driver or is a separate component that may be detached when it is desired to perform dry core drilling.
The water may be supplied to a masonry saw and core drill via a hose line connected to a remote water supply, e.g., a municipal water supply. However, for certain applications, e.g., where the sawing does not require a large supply of water or when a limited number of holes are to be drilled, a portable water supply, e.g., a pressurized ten-gallon tank of water, may be coupled to the saw or core drill.
Applying water aids the sawing process by cooling the cutting portion(s) of the saw device and removing saw residue from the work area. Similarly, injecting water into the core drill aids the drilling process by (1) cooling the drill, (2) facilitating movement away from the cutting head of the particles produced by the drilling operation so as to avoid unnecessary regrinding of those particles, and (3) reducing masonry dust in the work area. Consequently wet coring is preferred for renovation work in inhabited buildings where it is necessary to maintain a dust free environment. In such case it is common to surround the core drill with a water collector that serves to collect water, including suspended masonry particles, that escapes from the hole being drilled in the masonry. In core drilling of concrete, water may be supplied at a rate of as much as about 1 gallon per minute, whereas in wet sawing the water may be supplied at a rate as high as about 4 gallons per minute.
The speed at which cutting and drilling proceeds in concrete and other hard masonry materials is a function of the hardness of the material being cut or drilled. The harder the material, the lower the cutting or drilling speed, i.e., the rate of penetration of the material by the saw or drill head. It is recognized that increasing the cutting and drilling rates in concrete and other like structural materials is desirable, if it can accomplished at reasonable cost. Prior to the invention it was known that the cutting of concrete may be enhanced by applying an aqueous solution of one or more selected compounds to the cutting tool as it was cutting. See, for example, U.S. Pat. No. 5,196,401. However, there has existed a need for a practical, dependable and relatively inexpensive way of supplying a masonry saw or core drill with cooling water containing a measured amount of a cutting speed-enhancing compound.
The invention stems from the desire to improved the speed at which masonry saws and core drill cut or drill into structures or structural components made of masonry materials in the form of concrete, steel reinforced concrete, granite, sandstone, fired brick or like masonry material and consists of a novel method and apparatus for providing a stream of cooling water containing a cutting speed-enhancing composition. As used herein, the term xe2x80x9ccutting speedxe2x80x9d identifies the rate, in terms of units of depth per unit of time, at which a saw cuts through, or a core drill penetrates, a masonry material. More specifically, the invention involves use of a water-powered proportioning pump (also known as a xe2x80x9cdosing pumpxe2x80x9d) to introduce a metered amount of a speed-enhancing compound into a stream of cooling water as it is being applied to a masonry saw or core drill. In a first embodiment of the invention, a water-powered proportioning pump is connected in a pipe or hose line connecting a water supply to a core drill that is attached to an electrically or pneumatically powered driver, and a liquid speedenhancing surfactant-containing composition is injected into the water line by the proportioning pump. In a second embodiment of the invention, a waterpowered proportioning pump is connected in a pipe or hose line connecting a water supply to a masonry saw, and a speed-enhancing composition is injected into the water line by the proportioning pump. The method and apparatus of the invention provides that the speed-enhancing composition is injected into the water line in a measured rate, and also the speed-enhancing composition is deliver only on a demand basis.
Other objects, features and advantages of the invention are described or rendered obvious by the following detailed description which is to be considered together with the drawings identified below.